The present invention relates to a method of manufacturing free standing lead scandium tantalate thin films.
The fabrications of ceramic derived thermal detectors often requires the production of very thin slices of material. This is traditionally achieved by difficult and time consuming lapping and polishing techniques. In order to develop alternate routes to thin film ceramic, methods exploiting the recently developed metal organic precursors of these ceramics have been extensively utilised. These techniques include the deposition of thin films from metal organic solutions and by metal organic chemical vapour deposition (MOCVD). Both of these methods allow the controlled deposition of ceramic films with thicknesses less than 0.1 .mu.m.
These techniques have been successfully developed for material such as lead titanate and the preferred material Pb(Sc1/2Ta1/2)O.sub.3, (PST). A full account of the deposition methods has been described in patent Application No: PCT/GB89/00395.
The fabrication of free-standing PST films has been prevented previously due to the unavailability of a suitable substrate material. It has been successfully shown that PST can be readily grown in thin film form on substrates such as sapphire and gadolinium gallium garnet (GGG), as both possess coefficients of expansion very close to that of PST (6.5 ppm/K). However, both of these substrates are inert, in terms of device fabrication as both are difficult to remove.